1. Field of the Invention
This invention relates to measuring instruments and particularly to a tool for finding a vertical line for use by carpenters, builders, plumbers, and similar craftsmen.
2. Description of the Prior Art
There are many patents in the art of measuring instruments relating to tools for leveling and squaring functions, many using bubble type levels.
The Baher U.S. Pat. No. 3,826,013 describes a multi-purpose tool that may be used to level, square, and plumb various cylindrical, curved, inclined, and planar-shaped objects. This Baher tool has a body member with right-angular arms for forming a vertical elongated groove that is adapted to engage and accommodate any object, such as a post, rod, pipe, or conduit. There is also a horizontal shelf for supporting a bubble level or a target type "bulls-eye" liquid vial for use in leveling or plumbing an object being measured or positioned. A handle is disposed beneath the horizontal shelf for grasping by the user. This patent does not illustrate a means for attaching the tool to the object being measured so as to free up both hands of the user, as in the present invention.
The Dodson U.S. Pat. No. 2,541,641 describes an adjustable bubble level that is mainly for use in checking rotatable machine elements, such as shafts, pulleys, flywheels, fan rotors, gears, and the like. This patent has a base member in the form of an inverted V-block which is adapted to straddle and fit over the rotatable machine element such as a shaft. The V-block has a vertical post for supporting a vial yoke that in turn carries the level vial. The level of this patent is for determining a horizontal position, rather than in finding a plumb line, as in the present invention. The V-block of this patent is held to the shaft by means of a flexible chain that is attached at one end to the block, and at the other end is provided with an adjustable wing nut for engagement with the adjacent end of the V-block.
The Jackson U.S. Pat. No. 392,124 describes a spirit level that is capable of ready attachment to a vertical rod or plumb rules. A series of three wood screws are used for mounting the level to the vertical leveling rod or pole.
The Geier U.S. Pat. No. 2,356,311 describes an orbital bubble level of the general type that is employed in the present invention, and it is only one element of the combination which embodies the present invention. It is generally a commercially available item which happens to be useful in carrying out the present invention.
The Zipser U.S. Pat. No. 2,757,458 describes a bubble level for attachment to a portable electric drill, where the level may be angularly adjusted with respect to the drill so that the drill is capable of drilling holes at predetermined angles without requiring the use of a drill press.
The Weichert U.S. Pat. No. 2,806,296 is another patent showing a bubble level for attachment to a portable electric drill which enables the drill operator to guide the drill at any angle with respect to the horizontal.